Relatively short daily sessions of moderately intensive exercise raise testosterone levels, just like supplementation with moderate doss of BCAAs. And what has even more effect on testosterone levels is the combination of physical exercise and BCAAs, write biologists from Islamic Azad University in Iran in Andrologia. The researchers experimented with mice.

Study
The researchers divided male mice into different groups. In some groups, the mice ran 5 times a week for 45 minutes in a treadmill with an intensity of 70 percent of their maximum oxygen uptake, while other groups were not physically active.

Some groups of mice received BCAAs by the oral route. Mice in one group [20 mg of BCAAs] would have received 5-7 grams of BCAAs daily if they had been adult humans. Mice in the other group [60 mg BCAAs] would have received three times that dose if they had been human asults. Here you can read how you can calculate the human equivalent of a dose that researchers give to laboratory animals.

The test lasted 8 weeks.

Results
Daily training increased testosterone levels, but supplementation with a moderate dose of BCAAs increased the concentration of testosterone a little more. But the researchers found the highest concentrations of testosterone in the test animals that were not only physically active, but were also given a moderate dose of BCAAs.

Mechanism
The high dose of BCAAs had no positive effect on testosterone levels. The researchers suspect that modest BCAA supplementation makes the mitochondria in the cells of the testes work better, but that the administration of larger amounts damages the mitochondria.